Last year when I opened the fireplace flue for the first time in winter, several wasps fell down into the fireplace. They started to liven up in the warmth of the house, so they had to be killed quickly.
This year I made sure the have spray on hand when I opened the flue, and it's a good thing I did since there were probably about 50 of them this time. They were numbed by the cold, but they quickly started buzzing their wings, trying to take off. I used about a half a can, but I managed to kill them all before any of them escaped the fireplace.